Apparatus for graphing the elasticity of bows



Dec. 13, 1949 J. E. JAMES APPARATUS FOR GRAPHING THE ELASTICITY OF Bows Filed June '3, 1947 2 Sheets-Sheet 2 INVENTOR. a%/7 fit (26/726,?

ATTORNEVJ Patented Dec. 13, 1949 UNITED STATES PATENT OFFICE APPARATUS FOR GRAPHING THE ELASTICITY OF BOW'S Johnil. James, Kankakeefll.

Application 21mm 3, 1947, Serial No. 752,147

( Cl. f-33--1fl29 'iiClaims. El

invention relates to :an apparatus ier graphing the elasticity f bows, and has as its primary ubject the provision of a mechanical merrfla'er adapted to represent-graphically the relative strength and weakness or all portions of a bow Lr'im when under strain.

its conducive to a clearer understanding of this invention, it :mayhere be pointed out that in the manufacture of bowsga necessary elementof construction lies in the proper shaping and fashionrlativelyitimeconsumlng. A primary --object 0f thislinvention iis theprovis'ion of :a device adapted to be passedalong the show limbs, :and dur ing such passage to record graphically the weak and stiff sections over every point of each bow climb, in ordertorpermitirelativeradjustment of discrepancies, and more equalization of strain distribution in desired proportions.

A rfnrther (object pf the invention is the :pro-

'vdsinn of'a devioe :of character which is s'turdy and durable in construction, simple and inexpens'ive to manufacture, relatively easy to utilize, 'flll'd' BXiFI'EIIlHi-Y accurate :inzresults.

Still other objects reside in the combinations or elements, arrangements :of parts, and features of construction, zall as'zwill :be more zfully pointed out hereinaiiter rand disclosed in the accompanying idrawin'gswherein there is shown a preferred embodiment of inventive concept.

in @the drawings Figure :1 a top rpla-nvi'ewrof 'one form "of device embodying :ieatures er the iinstant invention.

:Eigurle i2 :is a side .elevational "view of the construction shown in Figure l, :'certain concealed portions tic-hereof being indicated in :dotted lines.

Figure 3 is a ireerielevational viewnf thezconstruction :shown :in Figures 1 and L2, as viewed from the lleit.

Figure 4 is a perspective view of a constructional detail.

Eigure 5 is a perspective view lofran additional constructional element.

reference characters refer to similar parts throughout the several views of the drawings.

'2 device of the instant invention comprises a body portion generally indicated at It, and comprised of two "separable halves, each including a longitudinally extending base member ll, provided at its rearward endwitha depending flange 12, and adjacent its rear end with a foot l3. Extending upwardly from each base portion H adjacent its rearward end is an inwardly curving arcuate member 14, the juncture of the two members forming anenlarged boss Ii-provided with a bore for the reception of a pivot pin 16, the purpose of which will be more fully described hereinafter. Forwardly of the boss '15, the sections merge into a longitudinally extending handle grip member I'! the handle portion terminating in outwardly flared members 18, which extend downwardly to the base -member 1-1. An arcuate guide bar I9 gonnec'ts the extremities of the flared lower mem- An enlarged boss adj acent'the rearward end of the frame members II and below the boss [5 of the handle portion I7 carries a pivot 20 against which is seated one end of a sleeve 2.1, the opposite end of "which is secured by the pointed :end '22 of pivot screw I'B. Thesleeve 2| forms the pivot for a bell crank member 25, the extremity "of which is provided with a sleeve 26 for "the accommodation of a pencil 21, 'or the "like, adapted to be biased downwardly therein, as by means of a rubber band '28, or the like. Also mounted on the sleeve 2| .is an adjusting member generally indicated at '30, and "including an aperturedboss 31 "through the aperture in which the sleeve 21 is adapted to pass, an extending arm "32 and'an uarcuate portion 3.3 provided on its inner "face with a plurality of notches. The notches 34 areadapted 'to be selectively engaged by'a stud 35 carried by the bell crank lever 25 and provided with a nut 26.

"Theleg 140 of bell crank member 25'beyond the p'ivo'tZl is provided with anaperture 4! adapted to have securedthere'to one end of a coil spring 42, the opposite end of which is suitably secured to a :pin carried by the frame H1. The extremity of the portion '32 of member '30 beyond the boss 3'1 "is inwardly turned in substantial alignment with the "arcuate portion 35, as indicated at *4'5, and "is adapted to abut 'a sho 48 having anarcuatesurface carried by a bell crank lever 41, pivotally connected, as by a pivot '48, to the portion 1 2 of "frame The extremity of the member t! beyond the pivot :38 carries a transversely extendin 'roller 49, to one extremity oi'whioh is secured a sprin 50, the-opposite end Seierring mow to #the drawings in detail, the secured to :9; pin 25! carried by the frame of the associated sleeve 25 and the pencil 21 carried thereby. Such movement of the pencil is indicated on a sheet of paper 60 carried by a plate 6i comprising the extremity of a channeled sheath 62 including inwardlyturned, upper flanges '53 adapted for the support of an elongated strip cc of graph paper.

Supporting means are provided for the device, and take the form of U-shaped members 54 and 65, including parallel bars, the upper extremities of the legs of the U being suitably secured between the portions 82 and the portions is of the frame members i i, respectively. 1 A vertically extending guide plate tie is adapted to be secured to the forward extremity of the side member H which carries bell crank member il and a projecting member 6! is secured to the rear end of the device, the extremity thereof being in substantial alignment with the guide bar 66.

Extending guide plate 6'; and member can be changed from one side of the apparatus tothe oth r to good advantage to accommodate right or left hand uses.

In the use and operation of the device, the bow is adapted first to be positionedon a tiller board, which, it may here be pointedout, is a vertically positioned backboard customarily utilized by bowyers upon which the bow is adapted to be clamped. In the operation of the device, the bow is clamped about an inch away from the board in unstressed position, a suitable sheet of graph paper inserted in the holder 62, and pinned to the center of the bow, and the device moved longitudinally of the bow 68. Obviously, any deviations in the surface of .the bow will be registered in the manner previously described by movement of the roller 39, and corresponding movement of the pencil 21 over the graph paper.

Th procedure may be repeated with both bow limbs, and an accurate graph line of the configuration of the bow in unstressed position obtained. Subsequent to this operation, tension is applied to the bow, and the procedure repeated. It will be readily apparent that the second graph will follow closely the contour of the first up to the point where the true bend of the bow limb begins, whereupon deviation will occur, but such deviation will follow in general the contour of the first graph, provided th strain, is proportionate throughout the length of the bow limb. Exceptionally weak or strong points will be marked by deviation in the graph line, and the exact position of such point may be determined by correlating the beginning of the graph line, as indicated by the pencil, with the exact position of the roller 59 on the bow limb, whereupon such deviations may be readily corrected in the customary manner,

From the foregoing it will now be seen that there is herein provided an improved devic of this character which accomplishes all the objects of this invention, and others, including many practical advantages. It ,will further be 4 obvious that a graphic representation of the entire surface of the bow may be readily obtained with a minimum of time, efiort and difiiculty.

As many embodiments may be made of this inventive concept, and as many modifications may be made in the embodiment hereinbefore shown and described, it is to be understood that all matter herein is to be interpreted merely as illustrative and not in a limiting sense.

I claim:

1. In a device of the character described, a

frame having side flanges and adapted to receive transverse roller secured to the lower arm and arranged beneath the frame for contact with a surface over which the frame is passed, a horizontally swinging lever pivotally mounted upon the frame, a spring connected with one end of the horizontally swinging lever, an adjusting element mounted upon the pivot'of the horizontally swinging lever and having a laterally extending crank engaged and moved by a part of the vertically swinging bell crank lever and having an arcuate portion, adjustable means carried by the horizontally swinging lever for securing the arcuate portion to such lever, and a marking device carried by the free end of the horizontally swinging lever.

2. In a device of the character described, a frame having side flanges and adapted to receive graph paper between the flanges, a vertically swinging bell crank lever pivotally mounted upon the frame and including upper and lower arms, a roller secured to the lower arm to contact with a surface over which the frame is passed, a horizontally swinging lever pivotally mounted upon the frame, a spring connected with one end of the horizontally swinging lever to move it in one direction, an adjusting element mounted upon the :pivot of the horizontally swinging lever and having a crank engaged and moved bya part of the vertically swinging bell crank lever and having an arcuate portion provided with spaced notches,

- a stud mounted upon the horizontally swinging lever to engage within a selected notch of the arcuate portion, and a marking device carried by the free end of the horizontally swinging lever.

3. In a device of the character described, a frame having side flanges and adapted to receive graph paper between the flanges, a ivertically swinging bell crank lever pivotally mounted upon the frame and including upper and lower arms, the lower arm having a part to contact with the surface over Which the frame is passed, a horizontally swinging lever, a vertical sleeve secured to the lever between its ends, pivot elements mounted upon the frame and engaging within the opposite ends of the sleeve, a spring connected with one end of the horizontally swingin lever to move it in one direction, a horizontally adjustable element mounted upon the vertical sleeve and having a crank engaged and moved by a part of the vertically swinging bell crank lever and an arcuate portion having spaced notches, a stud carried. by the horizontally swinging lever and engaging within a selected notch, and a marking device carried by the free end of the horizontally swinging lever. v 4. In a device of the character described, a frame having side flanges and adapted to receive graph paper between the flanges, a vertically swinging bell crank lever disposed upon the ex teri-or of the frame and pivotally mounted upon the side thereof and including upper and lower arms, a transverse roller carried by the lower arm to contact with the surface over which the fname is passed, a transverse extension carried by the upper arm, a horizontally swinging bell crank lever, a horizontally swinging adjusting element including a laterally extending crank and an arouate portion having spaced notches, common =pivot means for the horizontally swinging bell crank lever and the adjusting element secured tothe frame, a stud carried by the horizontally swinging bell crank lever and engaging in a selected notch of the ancuate pontion, a shoe carried by the transverse extension of the vertically swinging hell crank lever and engaging the cnank of 6 the horizontally swinging bell crank lever, a spring to swing the horizontally swinging bell crank lever in one direction, and a marking device carried by the horizontally swinging hell crank lever.

JOHN E. JAMES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,208,725 Balderson Dec. 19, 1916 2,372,662 Dewey Apr. 3, 1945 

